A former top Commonwealth Bank IT executive Keith Robert Hunter who has pleaded guilty to bribery offences over a mutimillion-dollar contract between the bank and a United States software company was "bankrupted and broken" into capitulation, according to an associate's lawyers.

Keith Robert Hunter, 62, a United States citizen, appeared briefly before Sydney's Downing Centre District Court on Friday where he pleaded guilty to two counts of bribery. He will appear for sentencing on December 5.

But lawyers for the head of a charity institution in the United States that NSW Police alleged made the wrongful payments to Mr Hunter, say the "unethical investigation" of Mr Hunter was "characterised by leaks of inaccurate, self-serving information" and had "bankrupted and broken Mr Hunter, apparently leaving him with no choice but to capitulate to the Australian government's demands".

Mr Hunter, the bank's former executive general manager of IT engineering previously pleaded not guilty to the offences but his turnabout with a guilty plea could mitigate the length of a potential jail sentence.

Mr Hunter was charged with bribery offences in March last year along with a colleague Jon Waldron. The two were accused of receiving about $2.9 million in bribes to award tens of millions of dollars worth of CBA's IT work to a United States software company, Servicemesh.

Mr Waldron, of New Zealand, was the bank's general manager of IT engineering. He faces seven counts of bribery and is next due before the Downing Centre District Court on July 21.

A statement by Mr Waldron's lawyer Phillip Gibson said while Mr Hunter pleaded guilty, Mr Waldron would continue to vigorously defend this case and his reputation.

The men were sacked from the bank and the matter was referred to NSW Police after an internal investigation into suspicious payments made to both men's bank accounts.

Mr Hunter and Mr Waldron were alleged by police to have received the money via payments to their CBA bank accounts by not-for-profit organisation called the ACE Foundation, which was set up by the founder of ServiceMesh Eric Pulier.

ServiceMesh, which was involved in multimillion-dollar deals with CBA from 2009, is a subsidiary of a major IT firm Computer Sciences Corporation.

CSC is pursuing Mr Pulier in the United States for the return of the $US260 million takeover price.

A statement by Mr Pulier's lawyer Mark Holscher of Kirkland & Ellis LLP in the United States said Mr Hunter consistently maintained his innocence and that he always acted in the best interests of his employer and that the payments he received were compensation for work he was undertaking for the ACE Foundation.

ACE's engagement with Mr Hunter was for work he was to perform for the ACE Foundation, under the explicit understanding that CBA was in approval, and the payments were made openly – to Mr Hunter's CBA account.

"It is insulting to the hard work and energy of so many who have devoted themselves to the foundation's ground-breaking results that these baseless allegations persist," Mr Holscher said.

"There was no relationship between the foundation's engagement with Mr Hunter and contracts with CBA in the past, and the complete openness of how it conducted business is evidence that nothing was meant to be hidden and all activities were understood as authorized."

He said the contract in question in the matter was vetted by scores of internal and independent parties on both sides, done at extremely favourable terms to the CBA, delivered in full and on time, and recently validated again as proper in all respects by Ernst & Young.

"CBA has agreed it has no claim to the foundation's money and will not keep it from being returned," Mr Holscher said.

A CBA spokesman said the bank reported Mr Hunter and Mr Waldron's conduct to the police in February 2015 because it considered the considered their suspicious activities as serious.

"We have cooperated with the police throughout their investigation and the proceedings and will continue to do so," the spokesman said.

Mr Waldron's lawyer, Mr Gibson said in the statement that Mr Waldron always said he was "never involved in any back room deals or bribery involving CBA and Servicemesh".

"Any payments he received were for legitimate work done for Ace Corporation and they were paid into an account in Mr Waldrons name at Auckland Savings Bank which is owned by CBA," Mr Gibson said.

"These transactions were completely transparent. There were no secret bank accounts in tax havens or any other indicia of corrupt payments."